Silica-based glass, such as soda-lime-silica glass, is prevalent in the manufacture of glass containers and other articles. Molten glass used to make such articles is conventionally prepared by melting various glass-forming materials in a furnace or tank at elevated temperature. During this process, gases (e.g., S02, C02, H20, etc.) are produced, which may evolve to form gas bubbles or “seeds” within the molten glass. The process of removing gas bubbles and/or dissolved gases from molten glass is referred to as “refining” or “degassing.”
A general object of the disclosure, in accordance with one aspect of the disclosure, is to provide an apparatus for refining molten glass that promotes the rapid release of gas bubbles therefrom and thereby reduces the time needed to refine the molten glass, or the “refining time.”
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
An apparatus for refining molten glass, in accordance with one aspect of the disclosure, includes: a housing and a guide positioned within the housing. The housing has a vertically oriented longitudinal axis, a transverse axis perpendicular to the longitudinal axis, an inlet at an upper end to receive molten glass, and an outlet a lower end to discharge molten glass therefrom. The guide has a flow surface upon which molten glass can flow between the inlet and the outlet of the housing. The flow surface of the guide has a surface area that is greater than a transverse cross-sectional area of the housing, and, when a volume of molten glass is introduced into the housing, the volume of molten glass is distributed over the flow surface of the guide such that the surface area of the volume of molten glass is increased and the thickness of the volume molten glass is decreased.
In accordance with another aspect of the disclosure, there is provided an apparatus for refining molten glass that includes: a housing having a vertically oriented longitudinal axis and a transverse axis perpendicular to the longitudinal axis, an inlet at an upper end of the housing to receive molten glass, an outlet at a lower end of the housing to discharge molten glass from the housing, and a guide extending at least partway across the housing. The guide directs molten glass in a generally downward direction through the housing and in a parallel or oblique direction relative to the transverse axis of the housing such that molten glass flowing from the upper end to the lower end of the housing moves relative to the longitudinal axis of the housing. In some embodiments, the molten glass may be directed through the housing such that the molten glass repeatedly intersects the longitudinal axis of the housing. In other embodiments, the molten glass may be directed by the guide such that the molten glass repeatedly passes from one side of the longitudinal axis of the housing to another, without physically intersecting the longitudinal axis. For example, the molten glass may be directed such that the molten glass repeatedly revolves around the longitudinal axis of the housing. In another embodiment, the guide may include a series of guides that direct the molten glass through the housing such that the molten glass cascades over the guides in succession.
In accordance with yet another aspect of the disclosure, there is provided a process for refining molten glass that includes: (a) introducing molten glass into an upper end of a housing having a vertically oriented longitudinal axis and a transverse axis perpendicular to the longitudinal axis, (b) flowing the molten glass over a guide such that the molten glass flows in a generally downward direction through the housing and in a parallel or oblique direction relative to the transverse axis of the housing, and then (c) discharging the molten glass from a lower end of the housing.